Automatic train-control system



' W. K. HOWE AUTOMATIC TRAIN CONTROL SYSTEM Original Filed April 3,. 1919 2 Sheets-Sheet 1 On m Car I 96 l l I 95 v On illilflli illl M 1 \EJ 41 15 1 I Fl G. 3 I im 3144) km @513 W 7'0. JZ

Feb. 10, 1925 1,526,294 w. K. HOWE AUTOMATIC THAIN CONTROL SYSTEM Original Filed April 5; 1919 2 Sheets-Sheet Z TTORNEY 'control the operation of the Patented Feb. 10, 1925.

I UNITED STATESPATENT OFFICE,

WINTHROP K. HOWE, ROCHESTER. NEW YORK, ASSIGNOR T0 GENERAL RAILWAY SIGNAL COMPANY, OF GATES, NEW YORK, A CORPORATION OF NEW YORK.

AI ITOMATIC TRAIN-CONTROL SYSTEM.

Original application filed April 3, 1919, Serial No. 287,132.

Divided and this application filed January 24, 1923. Serial No. 614,591.

'1 0 all rv/m it may concern:

c it known that I, WIN'rHRor K. Howe, a citizen of the United States of America; residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Automatic Clrain-Control Systems, of which 'the following is a specification.

This invention relates to automatic train control systems, and more particularly to the means for communicating from the track to the train the necessary and proper controlling influences.

ne of the essential features of any system of train control is an eiiicient and reliable means between the train control apparatus on the locomotive, or control means therefor, and the traiiic controlled elements along the track. which are subject to control by the presence of other trains or dangerous conditions ahead, such that the necessary controlling impulses or influences required to train control apparatus on the locomotive may be effectively transmitted whenever dangerous con ditions demand. Such means of communication between the track and a train should, it is believed, be one which acts inductively, that is, without any physical contact between any parts on the track and any parts on the train; and one of the principal objects of this invention is to provide a simple and reliable construction and arrangement oi" parts capable of transmitting, controlling influences by clectro-mac'nel'ic induction in such a way that the operation of the system will not be affected by weather conditions and can be arranged to operate satisfactorily with various clearances, types of rolling stock. and other practical working condi tions.

in connnunicatin; from the track to the train inductively it is believed expedient to employ as a track device an inert magnetic element. that is, a magnetic body which does not require electrical energy to maintain it in its active or its inactive condition. One. form of train control apparatus to coo n'era-te with an .inert'track elementot this for establishing communication or the like. which type comprises a core of suitable iron having a magnetizing winding and having suitable electro-responsive devices associated there with, whereby when this core passes over an inert track element along the track comprising a dead mass of magnetic material when in its active condition, the track element willchange the flux through the magnetic circuit of the car element on the vehicle, thereby inducing an electro-motiveforce which will affect the electro-responsivc device associated therewith.

In order to make this inert track element ineffective to produce operation of said electro-responsive device, a winding is pro-- vided on the track element which may be closed upon itself by suitable controlling devices whereby a choking effect is produced by the winding. lVhen a magnetized car element passes over the track clcment with its winding closed upon itself, the this through the magnetic core of the car element will not be changed appreciably, that is, a very slight change of flux through the track element will induce a cur-rent in the track element winding; causing a magnetoniotive-force which will counteract the 1nagneto-motive-force of the car-carried element, in consequence of which very little magnetism will link the two elements, and the electro-;espo11sive device on the train will not be operated.

The advantage of an inductive communicating system of this kind. is that no source of electrical energy is required for each trackelement along the track resulting in economy, especially when primarybatteries are used, and which makes a device which operates on the side of safety because an open circuit in the winding will cause an automatic actuation of the apparatus can ried on the train, whereby the train will be controlled. One of the disadvantages and. difliculties of an inductive system of this kind is the effect produced on the car-carried devices y other magnetic bodies, such as crossing rails, switch frogs, produce a similaraction communicating on the train carried element, and although fiiel'ile, may under C rtain conditions ca automatic control of the train. For convenience the effect of such foreign magnetic bodies along the track will be referred to as rail interferences throughout this specificanon.

With the above and other considerations in mind, the principal object and purpose it the present invention is to provide a carcarried device which is constructed and arranged in a manner not to be influenced by foreign magnetic objects, such as ralls, frogs, etc, but which will be influenced by comparatively short magnetic ob ects properly placed along the track, such as the inert track elements of magnetic material heretofore mentioned.

Other specific objects and features of this invention will appear hereinafter as the. description progresses, and the novel fea tales of the invention will be pointed out in the appended claims.

For the purpose of disclosing my invention l have illustrated in the accompanying drawings in asimplified' and diagrammatic way some. of the various forms which the devices embodying my invention may take, this illustration being selected more with a View to make it easy to understand the construction, operation and characteristic fea tures of a system embodying my invention, rather than with a view of showing the exact; construction of parts preferably used in practice. y

In describing the several modifications of my invention in detail, reference will be.

made to the which Fig. 1 shows diagrammatically one arrangement of the trackway circuits which accompanying drawings, in

may be used in the train control system em hodying my invention:

Fig. 2 shows a car-carried element which is constructed not to he improperly influenced by the track rails of a crossing, and one form of track element which is to cooperate therewith;

Fig. 3 illustrates another construction and arrangement of parts for preventing the car-carried element being improperly influenced by the'track rails of the crossings;

Fig. 4 illustrates a modified form of the trackway device which includes a battery;

Fig. 5 illustrates another construction and arrangement of' parts for preventing the carrarried element being improperly -in-- i'luencod by the track rails of crossings, crossovers-and the like, in which the main car-carried element is the same as shown in Fig. 8; and

Fig. 6 illustrates a system like that shown in Fig. 5, except that the car-carried element as shown in Fig. 2 has been substituted for the main car-carried element.

T his is a division of my prior application,.

Serial No. 287,132, for automatic train coa trol system, filed April 3, 1019. In describ ing several embodiments of the present invcntion, several forms of inert track elements will be described in connection with a wcll-known arrangement of trackcircuits and control devices for controlling the actuation of said track elements.

The trackway element T consists essentially ot' a U-shapcd core or yoke (see Fig. 2), having pole pieces 46 and two coils or windings 47 wound on the yoke below the pole pieces 46 in the same direction with respect to the core, or in other words, so that the voltages due to a change of flux in the core will be cumulative. This yoke 45 and pole pieces l6 are made of iron or other magnetic material, solid or laminated as conditions require. The pole pieces 46 are preferably disposed on the level, or just abo e the top of the heads of the track rails, so as to be as close as possible to the carcarried elementand yet be out of the way of all parts of the rolling stock. The trackway element T is given different controlling conditions, that is, is rendered capable of influencing or not influencing the car-carried element on a passing vehicle, by putting the coils 47 in an open circuit or in a deenergized closed circuit oflow resistance. While the circuit of the coils 47 maybe controlled in any suitable way, I have illustrated in Fig. 1 one form oftrackway circuits suitable for governing the controlling condition of the trackway element T in accordance with traiiic conditions.

Referring to Fig. 1, the track rails 48 are divided byinsulated joints 49 into blocks in the usual way, one block B with the adjacent ends of two other blocks A and C beingshown. The parts and circuits associated withthe various blocks A, B and C are the same, and for convenience will be given like reference characters with distinctive exponents. Each of the blocks is provided with a track battery and a track relay 50, the same as the ordinary .block signaling systems. Since my system of automatictrain control is preferably used in connection with the usual fixed signals of the wellknown automatic block signal system, such signals are indicated conventionally in Fig. 1; but the circuits and devices for controlling the indications and aspects of these fixed signals, being well-known in the art, have not been illustrated in order to avoid iulnecessary complication.

At a suitable distance in the rear of the pair of insulated joints 49 at the entrance of each block is located the trackway ele-- ment T (the normal direction of trailic being from left to right, as indicated by the arrow) and the circuit for the coils 47 of sand trackway element is controlledby the contact finger or armature of a line relay 51,

the controlling circuit of which includes inverted.U-shaped yokes In the trackway circuits shown neither the block B nor the block C is occuied, but is decner ized to open the circuit for the coils 47 when either of said blocks l3 or'C is occupied.

The particular form of trackway circuits shown in Fig. 1 is merely illustrative of thc manner in which the trackway elements of my system are controlled in order totransmit a cautionary impulse at each caution signal, and not transmit such a cautionary impulse at a clear signal. Obviously, various modifications and alterations may be made in the particular trackway circuits il- 'lustrated, it being evident that various expedients mayv be employed to assure the opening or closing of the circuit for the "coils at? of the trackway element T at si, z

naling points, depending upon traffic conditions in advance. Generally stated, the characteristic feature of the trackway circuits employed in my system of train control is that the coils-47 of the trackway element are in closed circuit at a clear signal, but are'open-circuited at a caution signal. in Fig. 1, the coils 47 of the trackway element are likewise open-circuited at a stop or danger signal, but this is not compulsory.

The car-carried element suitable for cooj'ierating with the trw-kway element T may take various forms, some of which have been shown. In the construction shown in Fig. 2, the structed in a manner not to be affected when the car on which it is mounted passes over track rails and other bodies. In this construction there are two X and X connezted at their middle points by a crossbar preferably of smaller cross-section than the leirs of said yokes X and X, forthe pur posc hereinafter explained. a

The legs of the yokes X and X are each provided with pole pieces 95 and a coil, as 96. 97, 98 and 99; The two pole pieces on the innermost adjacent logs of the yokes X and X are located at the proper distances apart to pass over the pole pieces 46 of the trackway element T shown; and the coils 97 and 98 on these legs are wound so that "their voltages add when a change of flux occurs through the path including the coil 98, crossbar and coil 97. The coils 9G and 99 are wound with respect to each other so that. their voltages add when a change of linx takes place throt'lgh the magnetic path through coil 96. bar V, and coil 99, but are so connected with the coils 97 and 98 that their voltages oppose the voltages of 97 and 98 when a change of flux througli'the two vneously. The coils 90,

car-carried element L is conforeign magnetic paths above referred to takes place simulta- 9T, 98 and 99 are connected in series in circuit with a battery 102 and the control relay R. On the legs of the crossbar \V are field coils 100, which are constantly energized from a battery 101 through a circuit includingthe winding of a check relay 56. The check relay 56 and the control. relay ll govern the operation of an electro-pneunmtic valve 1:. l. V which is adapted to slow down or stop the train in any suitable manner. This check relay 56 is a relay of any suitable or well-known eonslrlu-tion. which is capable of dropping itsarmalure 57 upon, a predetcrn'iined reduction in the amount ot current flowing through it to assure sate and proper opera tion of the system. which requires that the field coils 1-00 be energized and creating sutficient flux to insure inducing of current in the coils 97 and 98 when. the car passes an open-circuited trackway element.

The relay It comprises a coil (51 adapted to energize and attract a bar-armature or operating element 60, which is pivotally supported and provided on its opposite end with a striking piece 70 of insulating: inn-- terial, and is disposed between conta-t springs 71 and 71 which normally bear against contactpoints 72. so adjusted that when the magnet (51 ot' the relay is energized by a normal current, the contact springs 71 and 71 are both in contact with their respective contact points 72, the armature 60 being in a balanced posi tion. The striking piece is preferably made slightly shorter than the space between thecontact springs 71 and 71, in order that the armature (jOfmay have a slight movement from its middle balanced position before acting against said conta t springs. It will be evident that a decrease in the normal current throuo'hthc magnet (31 willpcrmit the spring (36 to over-lmlance the attraction of the armature (it), thus separating the bottom contact spring 71 from its contact point 72. It thecurrent through the magnet (31 is increased above that normally flowing, and to which the relay is adjusted, the attraction of them-mature (50 over-balances the opposition of the spring 66, thereby separating the other cooperating contactslil and T2. The circuit controlled by the relay lt passes from one contact spring 71 through the contact points 72 76, contact finger 57 0f the check relay 56,

The spring (36 h wire 77, magnet 17 of the E. P. V., and wire '78 back to the battery. The safe and proper operation of the system requires that the field coils 100 must be energized and creating sufficient flux to result in inducing current in the secondary coils 97 and 98,

when the car passes an opencircuited track-- way element, in the manner more fully explained hereinafter in the description of the operation. The check relay 56 insures the integrity of the circuit for energizing the field coils 100, since this relay will open its contacts whenever the current in this circuit falls below a predetermined value, due to the breaking of the circuit or depreciation of the battery 101. An excessive current in the field coils 190 will only serve to increase the inducing action, at least within narrow limits depending upon the design of the magnetic circuits and coils; and consequently, the check relay 56 may properly be a minimum current device.

In. order to afiord protection against crosses, short circuits, or the like, in connection with the energizing circuit for the field coils 100, the check relay should be similar in construction to the balanced type of relay R heretofore described. In a similar way the control. relay R checks the integrity of its circuit through the secondary coils 96, 97, 98 and 99, since any break or cross of the wires,or depreciation of the battery 102, results in opening the contacts of said control relay, due to the increase or decrease in the current normally flowing,

and for which said relay is adjusted. Thus, the balanced type of relay R not only acts as a device for detecting the current in duced in the secondary coils 97 and 98 under dangerous trafiic conditions, but also 1nsurcs that the current normally flowing in current sutiiciently to cause such a relay to drop away. Therefore, the use of a balanced type of relay, such as relay R shown, has the advantage that it. simplifies the system by combining in one device the requisite functions of a checking and detecting relay. Further, the construction of the re. lay R will cause a stopping of the tram it.

the battery voltage should be a-little too high, this stopping action being due to the effect of the seconu-haltof the cycle of the impulse received from the track element, which is in a direction to add to the voltage of the battery 102, thereby causing suflicient current to flow to attract the armature 60 and separate the contacts 71 and 72.

The operation of my inductive device for transmitting influences from the track to a passing vehicle, according to the construction shown in Fig. 2, is asv follo ws lVhen the car carried element L passes over the track element T, such as shown in Fig. 2, and the coils l7 of said trackway element T are o f)en-circuited, the flux through the secondary coils 97 and 98 is greatly changed to induce a current therein. If the crossbar W is made of such cross section as to be substantially saturated, the effect is increased, because with normal current flowing in. the coils 100, an increase in the flux through the coils 97 and 98 necessarily results in decreasing the flux through the coils 96 and 99, thereby inducing a voltage in these coils due to a decrease of flux; and since the coils 96-99 are wound oppos'itely to the coils 97-98 when considered in a magnetic circuit through these coils and the crossbar W, the voltage induced due to a decrease of flux through the coils 96 and 99 will add to the voltage induced due to an increase of flux through the coils 97 and 98, the path of flux in each instance being through the crossbar W. These induced voltages modify the current normally flowing through the winding of the control relay R, and cause it to open its contacts and operate the E. P. V.

If new the car-carried element shown in Fig. 2 should pass over a track rail of a crossing, the flux'through each of the four coils 96, 9?, 9S and 99 will be changed, that is, increased substantially alike; and since the coils 96 and 99- are wound oppositely to the coils 97 and 98 with respect to the magnetic paths through these coils and the crossbar I, the voltages induced therein will neutralize each other, thereby producing no operation of the control relay. The pole pieces of the car-carried element are preferably so located with reference to the trackway that the track rails of crossings, and the like ordinarily encountered, will influence the fiux'through these pole pieces substantially the same; and in any event, so that the eilect of such a track rail will be neutralized to such an extent that no op eration of the control relay will occur.

it a railway vehicle equipped with the car-carriedapparatus shown in'Fig. 2 passes over a track element in a, manner to assume the cooperatin relation, as shown inFig. 2,

and the coils l of the trackwayeleinent are. closed in a circuit of low resistance, no such control influence will be transmitted. This is attributed to the opposition or bucking action of the current induced in the closed circuited coil a7 of the trackway element 'l of the construction of the 1,52o,2ee

and prevents material change in the flux through the crossbar W and the legs containing coils 97 and 98.

In-Fig. 3 has been shown a modification car-carried element shown in Fig. 2. In this modifiedconstructmn, the field coils 100 are omitted and a single cross member or yoke lV connects the cores or legs upon which the combined field and secondary coils 96 97 98 and 99 are mounted. In view of the previous'discussion of the operation of the car-carried element sho n in Fig. 2, the operation of this modified construction will be evident without further explanation.

. In the various modified constructions hereinbefore considered, the trackway element T is changed from the clear to the caution controlling condition by open-circuiting its coils. This arrangement has the advantage that no energy is required along the track to control the trackway element and, change it trom a caution or stop to a clear controlling condition. This is a matter of considerable importance where the sources of current available along the trackway, such as the primary batteries used for the block signaling system, cannot be practicallyused to supply any eat amount of current for any prolonged time. If desired, however, the traclrway element ma be placed in condition'so as not to infl iience the. car-carried element on a passing train, by supplying current to its coils, as the'coils 47, to magnetize the yoke of said trackway element with, a polarit opposite to the polarity of the crossbar l of the car-carried element. Such a construction is shown in Fig". 4:, in

which the coils 4:? of the trackwayelement T are energized from a battery 104, or other source of current, when the line relay 51 is picked up.

Another arrangement for preventing an impulse being improperly transmitted at crossings, crossovers, and the like, is shown in Fig. In this arrangement. there are two car-carried elements M and N. The carcarried clement M is shown constructed the same asthat illustrated in Fig. 3; and the car-carried element N comprises a U-shaped core provided with coils 80 connected in circuit with a relay R similar to the relay R. and a battery A change in the reluctance of the magnetic circuit through the core will cause a momentary change of current in the circuit through the relay R thus opening the contact 71 or 71 depending upon thedirection of the induced to the volt-age oi' the battery 55.

Between the track rails 48 and in position to cooperate with the two inner cores of the car-carried element M, is a traclnvay' elen cnli T, the same as that shown in *ig. 2. At one side of the trackway element T, preferably on the outside of one of the track voltage with respect erated at each signaling point, irrespective of traflic conditions, since the mass of iron 0 always induces current in the coils of the car-carried element N. The control relay R is operated at the signaling points under dangerous trafiic conditions, but is not operated under clear traific conditions. Consequently, the E. I. V. is operated or not opera'ted at the signaling points depending upon trafiie conditions in advance.

It all of the pole pieces of the car-carried element M simultaneously pass over a mag nctic body, as the track rail of the right angle crossing (indicated at 105, Fig. 5), the control relay R is not operated forthe reasons hereinbefore explained in connection with the discussion of the construction shown in Fig. l/Vhen the track rail of a crossing or crossover extends at an an le across the main track rails, the successive 1nfluencing of the cores of the car-carried element M may, undercertain adverse circumstances, cause operation of the control relay R; but the angular position of the track rail required to do so is such that the car-carried element N time later or at some time earlier during the passage of the car. so that both of trol relays and R are not simultaneously operated. ,'or example, a tract: rail, asl06, positioned at such an angle that it may cause operation of the control relay R, will not influence the trackwayclement N and operate the control relay It until after the earcarried element M has moved beyond the influence of said track rail and the control relay R is closed.

It the track rail of the crossing or crossover is disposed at another angle, as indicated at 107, the relay R will be operated first, and then perhaps the relay R. In any event, the E. l V. is not operated. If conditions should arise where several foreign bodies of iron along the trackway are located withrespect to the track insubstam tially the same manner as the track elements 0 and '1, meet these elements may be modified by building magnetic material adjacent the same in a manner to cause a change of flux early enough not to'open one of the relays R and It at the same time the other of said relays is open.

,A system substantially the same as that shown in Fig 5 has been illustrated in Fig.

will be influenced either at some the con-v 6. The distinguishing feature of this system over the one shown in Fig. 5 resides in the employment of the car-carried element and associated parts shown in Fig. 2 to constitute the car-carried element M instead of the car-carried element and associated parts shown in Fig. 3.

Inview of the detailed discussion of the operation of Fig. 5, which is substantially the same as the system shown in Fig. 6, it is believed unnecessary to describe the operation of the system shown in the latter figure in detail. It may, however, be stated that the car-carried clement M of Fig. 6 acts upon the relays 56 and R, the same as does the device L of Fig. 2, and the elements N and (l are the same and function the same as the elements N and O of Fig. 5.

It should be noted that the operation of the system is dependent upon the functioning of deviceswhich have well recognized dependability. The reliable performance of track circuits and various other parts of automatic block signaling systems has been thoroughly established by long trial and experience, and the influence transmitting means and automatic train control apparatus of my system likewise consists of simple devices capable of accurate perform ance. Thus, without undue complication and expensive apparatus, 1 have provided a system in accordance with my invention which will obviate, to a large extent, if not entirely, the occurrence "of accidents upon railways and one that will be operated only by track elements when they are in their active condition.

In disclosing my invention I have selected simplified terms of construction, it being understood that various amplifications and modifications in accordance with good design and engineering practice would be made in the specific construction shown and described when putting my invention to practical use. For instance, the car-carried element L would be firmly secured to some appropriate part of the frame or running gear of the locomotive, motor car or other railway vehicle, and would be placed in a suitable casing to protect it from the weather.

The particular location and manner of supporting this car-carried element would vary upon different equipments, but in all cases an ample clearance of four or more inches above the level of the tops of the track rails could be readily provided, so that the car-carried element would not be struck or injured by the track rails at crossings, and the like, or by other similar projections usually encountered along railways. It will be evident that the distance of the car-carried element above the track rails will vary as the wheels of the vehicle wear down, or are replaced by new wheels; and I contemplate the provision of suitable means for adjusting the car-carried element ertically to compensate for such variations.

The trackway element is fastened securely in any appropriate manner to the ties of the track, either between or outside of the-track rails according to which arrange ment is best suited to the conditions of the particular installation, and this trackway element would be preferably housed and protected against dragging objects on passing-trains by a planking or housings of wood, or some non-magnetic material. The trackway element may be located at any desired point along the track where it is required to transmit a cautionary impulse to passing vehicles, and may be located at the approach to sharp curves, or other fixed hazards, as well as adjacent to the fixed signals ot' the block signaling system. 3!?

lVith the arrangement of tracltway circuits shown in Fig. 1, the trackway element may be located at any point with reference to the entrance of ablock, providing it is in the rear of the insulated joints at the entrance of the block, so that the vehicle will not stop itself in entering the bio-cl: and putting the trac may element in its caution controlling condition. It will be evident, however, that it a different a 'angement of trackway circuits is used, in which the trackway element at the entrance to 2;. block is not controlled by the track relay of that block, the various trackway eleme may be placed in advance of the lined nals if circumstances make it desirable to do so. The control relay R and the E. l": t would be placed in practice in a suitable t ing or cabinet on the vehicle and protects from jar and vibration by spring siiipports, or the like.

The various parts of the system in sealed or locked to prevent unauthoriz.v malicious tampering- With them; and ers and other well-known devices. ma used in connection with the system to clu up the care and vigilance used by the en neer. In short, various additions and modifications, obvious to those skilled in the art, may be made in the particular construction Til-3 shown and described without departing from my invention; and I desire to have it understood that the specific constructions and arrangement of parts and circuits shown and described are merely illustrative of my invention, and do not exhaust the various modifications of the idea of means constituting my invention.

That I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an automatic train control system, the combination with a car-carried element of an electromagnetic impulse transn'iitting means comprising, a partial magmatic cir cuit and coils adapted to be influen d by ries.

trackway and devices thereon comprising, a yoke having extending ing flux to said partial magnetic track element adapted to complete the parcircuits, electro-responsivc train non-magnetized magnetic bodies along the track, another partial magnetic circuit and coils adapted when influenced by non-magl ctlzltl magnetic bodies along the track to neutralize the influence in the first mentioned coils, of traflic ontrolled trackwav elements arranged to t-ioned coils but not the other coils under danger traffic conditions ahead.

2. Car equipment for automatic train control systems of the type in which controlling influences are communicated by magnetic cooperation between devices on the on the vehicle moving legs and having oppositely wound coils on two of-said legs, a circuit connecting said coils in series, and automatic train control means responsive to a change in the current in said circuit.

3. A car element for the inductive impulse transmitting means of train control systems provided with two oppositely wound coils and partial magnetic circuits therefor, a source-of magneto-motive-force for supplycircuits, a

tial circuit through one but not both of said coils, and train control means having an operating circuit connecting said coils in se- 4. A car element for inductively controlling automatic train control systems comprising working means and neutralizing means each adapted to be influenced bymag-- netic bodies along the track respectively co operating therewith, and a traflic controlled track element acting when in the acting stopping condition to influence said working means but not the neutralizing means, said .worlcing means and neutralizing means being arranged to be both influenced by magnetic: track rails disposed crosswise of the running rails.

5. In a train control system, a magnetic yoke carried on a car and provided with two partial magnetic circuits,-a source of iiiagiieto-niotive-it'orce for supplying flux to said control means on the car, oppositely wound coils associated with said magnetic circuits, said electro-responsive means being operated when one but not both of said partial magnetic circuits is completed, and a track element acting when in the stopping condition to complete one but not both of said partial circuits, said partial magnetic circuits bcing arranged to cause a track rail extending crosswise of the running rails to influence. both of them.

6. A ing partial magnetic circuitand a neutralizing partial magnetic circuit. trackway iri'eans acting to influence the working partial circuit but n bt the neutralizing partial influence the first men 7 track element uncer sate car-carried element having a work-- including a train control circuit-train control means. electro-responliicles by exchange of magnetic flux and in which a partial magnetic circuit on the car is completed by track elements in their ac,- tive stopping condition, the combination with said partial magnetic circuit, or clcc tr o-responsive meansoperable by a chain" of flux therein, another partial niagnc. circuit on the car, and means operable upon a change of flux in said another partial circuit for preventing operation of said cle tro-respon'sive means, whereby impu A not be improperly communicated or t track rails or other magnetic bodies on it track afiecting both partial circuits.

8. In a train control system car ci uin l he merit comprising a source of magneto-n'io-v tive-force, two partial magnetic circuits including said source, train control apparatus, control means responsivcto a change of flux in said two partial magnetic circuits for governing said apparatus,'said control means acting to cause operation of the apparatus when one but not both of said circuits is completed by magnetic bodies on the track, and traflic controlled trackw-ay elements constituting in the stopping condition a partial magnetic circuit cooperating with one but not both of the car-carried partial circuits.

In an automatic train control the combination with train control means on' a car set into operation by magi; bodies on the track of limited extend in not operated by bodies of larger extent, of track elements constituting in the stop 3;! condition a magnetic body of such limit-- system,

ed extent, and traffic controlled means for o posing the passa e of flux through said traflio conditions.

10. In an automatic train control system, the combination with automatic'train control means on a car rendered active by magnetic bodies extending part way across the track but not all of the way, of track elements comprising a magnetic yoke extencling part way across the track and having a winding thereon, and traific controlled means for opening and closing a decnergized circuit of low resistance through said winding.

11.. In an automatic train control system, the comb nation .of car carried apparatus device, two partial &

magnetic circuits each having a coil associated therewith, a normally energized electl'OIQSPOHSIVG device for governing said train control device connected in a circuit condition for inductively producing a voltage in one of said coils but not; in the other coil upon passage of thetrainthereby under danger tralflc conditions ahead, said coils being connected in series so that simultaneous changes in fluxes thcrethrough due to simultaneous passage over nonmagnetized 'l'llilQl'lElTlC body produces counter-acting voltages in saidcircuit.

12. Cancarried apparatus for automatic train control systems comprising, a normally energized train control device, two separate normally energized electro-responsive devices each ofwhich if energized alone maintains said train control device energized, a separate inductive influence communicating device for each of said electro-' responsive devices, each of said influence communicating devices including a millecated in inductive relation with the track- Way and adapted to have apotential induced therein upon the passage of the train by a suitable trackway device, whereby said train control device is actuated only if inductive control influences are received by both simultaneously.

13. In a train control system, the combination of a track divided into blocks, in ductive influence communicating means at each control point including a plurality of track elements eachelement of which comprises a mass of inert and unmagnetized iron when in its,active influence transmitting condition, and car-carried apparatus comprising two influence receiving coils located to simultaneouslycooperate with said track elements upon the passage of the train by a control point and eachof which is adapted to have a voltage induced therein by reason of a car-carried source of magneto-motive-force when passing by a track element, and a normally energized electroresponsive device which isdeenergized only of said electro-responsive devices magnetic bodies of a larger extent having a flux producing coil for producing a field of flux which is necessary to transmit such control influences, an electro-responsive device connected in circuit with said flux producing coil which if deenergized will cause an application of the brakes, said device hav ing a dropaway characteristic so that it will assume its deenergized position when the current in said flux producingcoil falls so low that insuflicient flux will be present for transmitting control influences, a traclzway element constituting a magnetic body of the same limited extent, and trafllc controlled means for opposing the passage of flux through said track elements under safe trattic conditions.

15. In an automatic train control system, the, combination with a track element contstituting a partial magnetic circuit when in the stopging condition, of an engine element comprising a yoke having extending legs, oppositelv wound coils ontwo legs of. said yoke an connected in series, both of said coils being subjected to substantially the same influence when the engine element passes over extraneous magnetic bodies along the track, only one coil being under the influence of the regular track elements,

and electro-responsi've means on the engine connected to said coils.

16. In an automatic train control system, the combination of car-carried apparatus including a train control device, two partial magnetic circuits each having a magnetomotive force induced therein and a coil as sociated'therewitli, a normally energized electro-responsive device for governing said train contr '1 device connected in a circuit in series wth taid coils, and of trackway means contrjolled in accordance with traiiic conditions ahead and consisting of a nonmagnetic body when in its active condition located to inductively produce a voltage in one of said coils but not in the other coil upon passage of such vehicle thereby under danger trallic conditions ahead, said coils being connected in series so that simultaneous changes in fluxes therethrough produces counter-acting voltages in such circuit, whereby voltages induced in said coils, due to the passing of ma netic bodies of considerable length and in uencing both of said coils, neutralize each other.

17 In an automatic train control system, the combination of car carried apparatus comprising, an electro-responsive device, an inductive influence receiving device located so as to inductively communicate with magnetic bodies along the trackway havin coils associated therewith connected to said electro-responsive device, said inductive device and coils being correlated so that said electro-responsive device is actuated if a short magnetic body is passed over but is not aclit iceeeee e tested it a magnetic loodyof greater extent then said inductive device is passed over, and e. treflic controlled treckvvey device comprising, a short non-magnetized magnetic lacdy wiien in on active condition for ac tueting seid electrc-responsive device under dimger treliic conditions ahead.

l8 {lair carried apparatus for automatic llilllfl control systems comprising, a. core of magnetic material having four coils sssocieted therewith a source of nmgnetoenotive-iorce acting upon said core, on electr0- responsive device, a circuit including said electro-i'cspoiisive device and said coils in series so that 21 change of flux in all of said coils dueto said magneto-motivedorce upon passing over a car of magnetizable material "produces counter-acting voltages in said circuit, whereby said electro-responsive device is actuated ii a change of flux n1 certain of said cells only 1e efiected by the passage of said core over at magnetic body of limited length.

19. In on automatic train control system connected to one of said electro-responsive devices, a train control. device having a. mdmg, and a circuit for energizing said train control device including" in series at source of energy, the Winding of said tmin control device, and a partial circuit including the two contacts of said electro-responsive devices connected in multiple.

In testimony whereof I hereby a lfix my signature.

' WINTHROP K. HOWE. 

